How was the flood during Noah's time just?

TL;DR:

The flood was just because God judged widespread evil in perfect holiness, not out of rage but righteousness. At the same time, God showed mercy by saving Noah, offering hope even in judgment.

God's judgment against wickedness is just because it aligns with His character as a holy and just God (Psalm 92:15). When faced with injustice, a just God casts judgment to restore righteousness. This judgment is not for the sake of punishment alone but is an invitation for reconciliation and correction, motivated by compassion rather than revenge.

The flood is an act of both divine justice and mercy. Justice is served by eliminating the violence, suffering and wickedness that had spread throughout the earth (Genesis 6:5; 6:13). God showed mercy by preserving righteous Noah and his family, as well as the animals, to repopulate the earth (Genesis 7:1; 9:1).

from the old testament

Genesis 6:5-6 tells us God observed the extent of human wickedness. He saw that everything they thought or imagined was consistently and totally evil. Because of the great wickedness and violence, God told Noah that He was going to destroy all living creatures (Genesis 6:13).Yet because of God's mercy He instructed Noah to build an ark to save himself and his family. Noah did everything exactly as God had commanded him (Genesis 6:14-22). God’s actions were just and merciful.
God is just. There is no wickedness in Him (Psalm 92:15). Since God is just, His actions, including the flood are just.
Not only is God just, He expects the same of us. God requires us to act justly, to love mercy and to walk humbly with Him (Micah 6:8).

from the new testament

The writer of Hebrews lists Noah among the Old Testament faithful for following the Lord’s command to build the ark to save his family from the flood. Noah obeyed God, who warned him about things that had never happened before. Noah received the righteousness that comes by faith (Hebrews 11:7).
Noah was a preacher of righteousness. Those who came in contact with Noah had the opportunity to repent and turn toward the Lord and be saved. Instead, they continued in their evil and violent ways. God protected Noah when He destroyed the world of ungodly people with the flood (2 Peter 2:5).
Jesus likened His Second Coming to the “days of Noah” in that people blithely continued with their own life, uncaring of the Lord and the coming judgment (Luke 17:23). Preaching the gospel is so imperative because of that coming judgment.

implications for today

Besides the flood, the Bible provides many other examples where God's judgment is seen as a response to severe sin. God judged the people of Canaan with a command to wipe them out (Deuteronomy 20:16-18). He similarly judged Sodom and Gomorrah (Genesis 19:24-25), Nineveh (Nahum 1:14), and Tyre (Ezekiel 26:4). And the final judgment before the Great White Throne will result in all the wicked from all time being cast into the lake of fire (Revelation 20:11-15). The plain message of the Bible is that God does judge sin, whether by an invading army, by fire and brimstone, or by a catastrophic global flood. Even when God's judgment seems harsh, it reflects His commitment to justice and His desire to protect and redeem His people.

Even with a new beginning after the flood, humankind still needed God's intervening hand of salvation. Paul explained to the Romans, "for all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith" (Romans 3:23–25). Jesus' sacrifice on the cross paid the penalty for sin; His resurrection confirmed it. When we receive Jesus' work on our behalf by faith, we are made right before God, and it results in our sanctification and eternal life (Romans 6:22).

understand

God’s character is holy and just, so His judgments are as well—including the flood.
The flood was a just punishment for the wickedness of humanity.
Rather than destroy us (as would have been just) as God did during Noah’s day, God sent His Son to atone for our sins; those who put faith in Christ are covered with His righteousness, which satisfies God’s justice.

reflect

How does God's justice concerning the flood help you to better understand His character?
How does the biblical account of the flood help you to better understand human nature?
How does the flood narrative help you better appreciate what Christ has done for humanity?

engage

What challenges to God’s character have you encountered, specifically regarding the flood account?
How can the flood narrative be used as a springboard for sharing the good news of Christ?
What aspects of God’s character can you help others understand with the flood narrative?